Effector-Independent Motor Sequence Representations Exist in Extrinsic and Intrinsic Reference Frames

Wiestler, Tobias; Waters-Metenier, Sheena; Diedrichsen, Jörn

doi:10.1523/jneurosci.5363-13.2014

Cited by 78 publications

(99 citation statements)

References 55 publications

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“…However, the fact that iTBS applied to the untrained hemisphere amplified untrained hand performance gains in the current study suggests that some form of adaptation occurred within the untrained M1 that mediated performance improvements in the untrained hand. In support of this view there is evidence from neuroimaging data on the encoding of (sequential) single finger movements Wiestler et al 2014) demonstrating similar (mirrored) representation patterns in both motor cortices (and sensory motor cortices) that include the same fine-grained details of the movement, but with suppressed blood oxygen level-dependent (BOLD) signals (relative to resting baseline) in the motor cortex ipsilateral to the active hand. This raises the possibility that multiple processes may influence ipsilateral cortical function, including generalized suppression of activation (which might underlie the lack of corticospinal excitability we observed) and patterned activation specifically associated with task performance (which might underlie transfer of performance to the untrained limb).…”

Section: What Type Of Ipsilateral Adaptations Mediate Untrained Hand mentioning

confidence: 89%

Motor learning and cross-limb transfer rely upon distinct neural adaptation processes

Stöckel

Carroll

Summers

et al. 2016

Journal of Neurophysiology

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Performance benefits conferred in the untrained limb after unilateral motor practice are termed cross-limb transfer. Although the effect is robust, the neural mechanisms remain incompletely understood. In this study we used noninvasive brain stimulation to reveal that the neural adaptations that mediate motor learning in the trained limb are distinct from those that underlie cross-limb transfer to the opposite limb. Thirty-six participants practiced a ballistic motor task with their right index finger (150 trials), followed by intermittent theta-burst stimulation (iTBS) applied to the trained (contralateral) primary motor cortex (cM1 group), the untrained (ipsilateral) M1 (iM1 group), or the vertex (sham group). After stimulation, another 150 training trials were undertaken. Motor performance and corticospinal excitability were assessed before motor training, pre-and post-iTBS, and after the second training bout. For all groups, training significantly increased performance and excitability of the trained hand, and performance, but not excitability, of the untrained hand, indicating transfer at the level of task performance. The typical facilitatory effect of iTBS on MEPs was reversed for cM1, suggesting homeostatic metaplasticity, and prior performance gains in the trained hand were degraded, suggesting that iTBS interfered with learning. In stark contrast, iM1 iTBS facilitated both performance and excitability for the untrained hand. Importantly, the effects of cM1 and iM1 iTBS on behavior were exclusive to the hand contralateral to stimulation, suggesting that adaptations within the untrained M1 contribute to crosslimb transfer. However, the neural processes that mediate learning in the trained hemisphere vs. transfer in the untrained hemisphere appear distinct. ballistic motor learning; interlimb transfer; noninvasive brain stimulation; corticospinal excitability; motor performance

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Section: What Type Of Ipsilateral Adaptations Mediate Untrained Hand mentioning

confidence: 89%

Motor learning and cross-limb transfer rely upon distinct neural adaptation processes

Stöckel

Carroll

Summers

et al. 2016

Journal of Neurophysiology

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“…A part of this kind of transfer could potentially depend on motor representations because sequence practice with one effector has been found to have a bilateral effect in the primary motor cortex (Wiestler et al, 2014). Hence, we cannot be entirely sure what type of representation facilitates transfer between mirrored movements.…”

Section: Introductionmentioning

confidence: 99%

Similar Representations of Sequence Knowledge in Young and Older Adults: A Study of Effector Independent Transfer

et al. 2016

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Older adults show reduced motor performance and changes in motor skill development. To better understand these changes, we studied differences in sequence knowledge representations between young and older adults using a transfer task. Transfer, or the ability to apply motor skills flexibly, is highly relevant in day-to-day motor activity and facilitates generalization of learning to new contexts. By using movement types that are completely unrelated in terms of muscle activation and response location, we focused on transfer facilitated by the early, visuospatial system. We tested 32 right-handed older adults (65–75) and 32 young adults (18–30). During practice of a discrete sequence production task, participants learned two six-element sequences using either unimanual key-presses (KPs) or by moving a lever with lower arm flexion-extension (FE) movements. Each sequence was performed 144 times. They then performed a test phase consisting of familiar and random sequences performed with the type of movements not used during practice. Both age groups displayed transfer from FE to KP movements as indicated by faster performance on the familiar sequences in the test phase. Only young adults transferred their sequence knowledge from KP to FE movements. In both directions, the young showed higher transfer than older adults. These results suggest that the older participants, like the young, represented their sequences in an abstract visuospatial manner. Transfer was asymmetric in both age groups: there was more transfer from FE to KP movements than vice versa. This similar asymmetry is a further indication that the types of representations that older adults develop are comparable to those that young adults develop. We furthermore found that older adults improved less during FE practice, gained less explicit knowledge, displayed a smaller visuospatial working memory capacity and had lower processing speed than young adults. Despite the many differences between young and older adults, the ability to apply sequence knowledge in a flexible way appears to be partly preserved in older adults.

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“…Assessing the selectivity of motor neural populations in humans is possible through the use of multivariate pattern analysis (MVPA) techniques applied to voxel-by-voxel fMRI responses (Dinstein et al, 2008;Gallivan et al, 2011;Kadmon Harpaz et al, 2014;Wiestler et al, 2014). Several recent fMRI studies have reported that directionally selective responses are apparent in human M1 (Cowper-Smith et al, 2010;Eisenberg et al, 2010;Fabbri et al, 2010;Toxopeus et al, 2011), PMd (Cowper-Smith et al, 2010;Fabbri et al, 2010), SMA (Cowper-Smith et al, 2010), and PPC (Fabbri et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Dissociating Visual and Motor Directional Selectivity Using Visuomotor Adaptation

2015

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Directional selectivity during visually guided hand movements is a fundamental characteristic of neural populations in multiple motor areas of the primate brain. In the current study, we assessed how directional selectivity changes when reaching movements are dissociated from their visual feedback by rotating the visual field. We recorded simultaneous movement kinematics and fMRI activity while human subjects performed out-and-back movements to four peripheral targets before and after adaptation to a 45°visuomotor rotation. A classification algorithm was trained to identify movement direction according to voxel-by-voxel fMRI patterns in each of several brain areas. The direction of movements was successfully decoded with above-chance accuracy in multiple motor and visual areas when training and testing the classifier on trials within each condition, thereby demonstrating the existence of directionally selective fMRI patterns within each stage of the experiment. Most importantly, when training the classifier on baseline trials and decoding rotated trials, motor brain areas exhibited above-chance decoding according to the original movement direction and visual brain areas exhibited above-chance decoding according to the rotated visual target location, while posterior parietal cortex (PPC) exhibited chance-level decoding according to both. These results reveal that directionally selective fMRI patterns in motor system areas faithfully represent movement direction regardless of visual feedback, while fMRI patterns in visual system areas faithfully represent target location regardless of movement direction. Directionally selective fMRI patterns in PPC, however, were altered following adaptation learning, thereby suggesting that the novel visuomotor mapping, which was learned during visuomotor adaptation, is stored in PPC.

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Effector-Independent Motor Sequence Representations Exist in Extrinsic and Intrinsic Reference Frames

Cited by 78 publications

References 55 publications

Motor learning and cross-limb transfer rely upon distinct neural adaptation processes

Motor learning and cross-limb transfer rely upon distinct neural adaptation processes

Similar Representations of Sequence Knowledge in Young and Older Adults: A Study of Effector Independent Transfer

Dissociating Visual and Motor Directional Selectivity Using Visuomotor Adaptation

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